Revert 113282 - Isolates generic DnsClient from AsyncHostResolver.

net/dns/dns_transaction.h

Index: net/dns/dns_transaction.h
===================================================================
--- net/dns/dns_transaction.h	(revision 113383)
+++ net/dns/dns_transaction.h	(working copy)
@@ -6,10 +6,12 @@
 #define NET_DNS_DNS_TRANSACTION_H_
 #pragma once
 
+#include <set>
 #include <string>
+#include <utility>
 #include <vector>
 
-#include "base/memory/ref_counted.h"
+#include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/timer.h"
 #include "base/threading/non_thread_safe.h"
@@ -21,39 +23,70 @@
 
 namespace net {
 
+class ClientSocketFactory;
 class DatagramClientSocket;
 class DnsQuery;
 class DnsResponse;
-class DnsSession;
 
-// Performs a single asynchronous DNS transaction over UDP,
+// Performs (with fixed retries) a single asynchronous DNS transaction,
 // which consists of sending out a DNS query, waiting for a response, and
-// returning the response that it matches.
+// parsing and returning the IP addresses that it matches.
 class NET_EXPORT_PRIVATE DnsTransaction :
     NON_EXPORTED_BASE(public base::NonThreadSafe) {
  public:
-  typedef base::Callback<void(DnsTransaction*, int)> ResultCallback;
+  typedef std::pair<std::string, uint16> Key;
 
-  // Create new transaction using the parameters and state in |session|.
-  // Issues query for name |qname| (in DNS format) type |qtype| and class IN.
-  // Calls |callback| on completion or timeout.
-  // TODO(szym): change dependency to (IPEndPoint, Socket, DnsQuery, callback)
-  DnsTransaction(DnsSession* session,
-                 const base::StringPiece& qname,
-                 uint16 qtype,
-                 const ResultCallback& callback,
-                 const BoundNetLog& source_net_log);
-  ~DnsTransaction();
+  // Interface that should be implemented by DnsTransaction consumers and
+  // passed to the |Start| method to be notified when the transaction has
+  // completed.
+  class NET_EXPORT_PRIVATE Delegate {
+   public:
+    Delegate();
+    virtual ~Delegate();
 
-  const DnsQuery* query() const { return query_.get(); }
+    // A consumer of DnsTransaction should override |OnTransactionComplete|
+    // and call |set_delegate(this)|.  The method will be called once the
+    // resolution has completed, results passed in as arguments.
+    virtual void OnTransactionComplete(
+        int result,
+        const DnsTransaction* transaction,
+        const IPAddressList& ip_addresses);
 
-  const DnsResponse* response() const { return response_.get(); }
+   private:
+    friend class DnsTransaction;
 
+    void Attach(DnsTransaction* transaction);
+    void Detach(DnsTransaction* transaction);
+
+    std::set<DnsTransaction*> registered_transactions_;
+
+    DISALLOW_COPY_AND_ASSIGN(Delegate);
+  };
+
+  // |dns_server| is the address of the DNS server, |dns_name| is the
+  // hostname (in DNS format) to be resolved, |query_type| is the type of
+  // the query, either kDNS_A or kDNS_AAAA, |rand_int| is the PRNG used for
+  // generating DNS query.
+  DnsTransaction(const IPEndPoint& dns_server,
+                 const std::string& dns_name,
+                 uint16 query_type,
+                 const RandIntCallback& rand_int,
+                 ClientSocketFactory* socket_factory,
+                 const BoundNetLog& source_net_log,
+                 NetLog* net_log);
+  ~DnsTransaction();
+  void SetDelegate(Delegate* delegate);
+  const Key& key() const { return key_; }
+
   // Starts the resolution process.  Will return ERR_IO_PENDING and will
   // notify the caller via |delegate|.  Should only be called once.
   int Start();
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(DnsTransactionTest, FirstTimeoutTest);
+  FRIEND_TEST_ALL_PREFIXES(DnsTransactionTest, SecondTimeoutTest);
+  FRIEND_TEST_ALL_PREFIXES(DnsTransactionTest, ThirdTimeoutTest);
+
   enum State {
     STATE_CONNECT,
     STATE_CONNECT_COMPLETE,
@@ -81,17 +114,26 @@
   void RevokeTimer();
   void OnTimeout();
 
-  scoped_refptr<DnsSession> session_;
-  IPEndPoint dns_server_;
+  // This is to be used by unit tests only.
+  void set_timeouts_ms(const std::vector<base::TimeDelta>& timeouts_ms);
+
+  const IPEndPoint dns_server_;
+  Key key_;
+  IPAddressList ip_addresses_;
+  Delegate* delegate_;
+
   scoped_ptr<DnsQuery> query_;
-  ResultCallback callback_;
   scoped_ptr<DnsResponse> response_;
   scoped_ptr<DatagramClientSocket> socket_;
 
   // Number of retry attempts so far.
-  int attempts_;
+  size_t attempts_;
 
+  // Timeouts in milliseconds.
+  std::vector<base::TimeDelta> timeouts_ms_;
+
   State next_state_;
+  ClientSocketFactory* socket_factory_;
   base::OneShotTimer<DnsTransaction> timer_;
   OldCompletionCallbackImpl<DnsTransaction> io_callback_;